Air Resistance for A Body

I can't seem to come up with a decent formula/accepted value for air resistance.

I realize there are things that need to be taken into account, but I am already delving into things way beyond what I've done per the course work, and I don't want to bite off more than I can chew. I understand there is no exact formula for air resistance, but I need a number to find a terminal velocity.

Staff: Mentor

Well what happens at terminal velocity? It means that the velocity doesn't increase, othewise it wouldn't be terminal velocity. If velocity doesn't increase, there is no acceleration, and that means that the net force of the falling object is zero, which means the Drag Force, D, must equal the weight of falling object.

So D = mg, and looking at the NASA site [tex]D\,=\,C_d\frac{\rho{V^2}A}{2}[/tex],

where [itex]\rho[/itex] is the density of air, V is the velocity of the object in the air, A is the cross-sectional area normal to the flow (or trajectory), and Cd is the drag coefficient.